Registers
A register consists
of a collection of binary storage cells, each implemented by a flip-flop.
The number of cells determines the length of the register and, therefore,
the length of the binary word stored within the register. Thus, an bit
register contains n flip flops and can store n bits ( 2^n binary combinations,
or distinct states.)
Operation associated
with a register:
-
Write (Load):
To load bits of information into the register. Each information bit is
input to one of the registers.
-
Read: Reading
the content of the register. We simply access the Q output of the register.
Parallel register
Since the read and
write operations are applied to all the cells simultaneously, the register
is called parallel register.
Three bit parallel register
Parallel to serial register:
-
g=0: Di receive the
Pi value. This is the step of getting the parallel signal. All the flip
flop should receive their values .
-
g=1: Di receive the
Qi-1 value. This is the serial step.
Shift register:
A shift register
consist of flip flops connected such that the output of one flip flop feeds
the input of the next flip flop. The clock input of all the flip flops
is connected to a common clock pulse source. The number of flip flops
in the chain determines the length of the shift register.
Four bit shift register (also- 'serial to parallel'.)
Serial Binary
adder
Note:
- The upper register is receiving the
input from s so at the end the shift register will contain the output.
- The button D-FF retain the array bit
from the next clock.
Implementing sequential system using shift register
Implementing detection
of without overlapping "10010":
|